Injectors for internal combustion engines usually comprise a valve body which must be resistant to the pressures within the injector and, at the same time, capable of guiding a magnetic flux created by a coil of the injector. The valve body itself is typically ferromagnetic which causes the problem that a magnetic flux bypass through the ferromagnetic valve body wall is created. Such a magnetic flux bypass causes a general worsening of injector dynamic responses.
In order to overcome this disadvantage, paramagnetic valve bodies which shield impervious the magnetic flux have been applied in injectors. These paramagnetic valve bodies reduce the overall efficiency of a magnetic circuit of the injector and worsen any injector dynamic response due to a big radial gap between armature and housing as well as washer and housing.
Another possible solution for overcoming said disadvantage is described in document GB 2 262 659 A in which a non-magnetic portion is positioned between two magnetic portions of the valve body. Although such a solution reduces the magnetic flux bypass, mechanical properties, and—as a result—the resistance to pressure is reduced as well.